Inelastic excitation of <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi mathvariant="normal">C</mi></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>12</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow></math></span> and <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi mathvariant="normal">N</mi></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>14</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow></math></span> by 122 MeV protons and implications for the effective nucleon-nucleon interaction

J. R. Comfort; Sam M. Austin; P. T. Debevec; G. L. Moake; R. W. Finlay; W. G. Love

doi:10.1103/PhysRevC.21.2147

Inelastic excitation of ${}^{12}C$ and ${}^{14}N$ by 122 MeV protons and implications for the effective nucleon-nucleon interaction

J. R. Comfort, Sam M. Austin, P. T. Debevec, G. L. Moake, R. W. Finlay, and W. G. Love

Phys. Rev. C 21, 2147 – Published 1 June 1980

Abstract

Cross sections for the ${}^{12}C$ ( $p$ , $p^{'}$ ) ${}^{12}C$ and ${}^{14}N$ ( $p$ , $p^{'}$ ) ${}^{14}N$ reactions have been measured at $E_{p} = 122$ MeV. Scattered protons were momentum analyzed in a dispersion-matched magnetic spectrograph and detected in a helical-cathode position-sensitive proportional counter. Transitions to states in ${}^{12}C$ at 4.44 MeV ( $2^{+}$ , $T = 0$ ), 12.71 MeV ( $1^{+}$ ,0), 15.11 MeV ( $1^{+}$ ,1), 16.11 MeV ( $2^{+}$ ,1), and in ${}^{14}N$ at 2.31 MeV ( $0^{+}$ ,1) and 3.95 MeV ( $1^{+}$ ,0), are very useful for studying the spin-isospin dependence of the effective two-nucleon interaction. Cross sections for these states from the present experiment and from earlier measurements at 185 MeV have been analyzed in the distorted-wave impulse approximation. Simultaneous consideration of ( $e$ , $e^{'}$ ) data for the same transitions helped to disentangle some nuclear-structure and reaction-mechanism effects. The distorted-wave impulse approximation provides a good description of those transitions in ${}^{12}C$ mediated predominantly by the $S = T = 1$ part of the effective interaction and also gives a reasonable description of the $S = T = 0$ transitions in both nuclei. The mechanisms for excitation of the 12.71-MeV state in ${}^{12}C$ ( $S = 1$ , $T = 0$ ) and the 2.31-MeV state in ${}^{14}N$ ( $S = 1$ , $T = 1$ ) remain a puzzle.

NUCLEAR REACTIONS ${}^{12}C$ , ${}^{14}N$ ( $p$ , $p$ ), ( $p$ , $p^{'}$ ), $E = 122$ MeV; measured $σ (E_{p}, θ)$ ; resolution 100 keV; $θ = 6 - 60 °$ . ${}^{12}C$ $2^{+}$ states deduced $β_{2}$ DWIA analysis; microscopic effective interaction with $\vec{L} \cdot \vec{S}$ , tensor, and exchange terms.